SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '738f4e16f2a0a9e194738c91c97e93a6c33e3b5045c10af1ee868a125b26deb5' 
  AND token = 'wxdFqrzRdYbHSfST/+QMgVAHpuSj0GAvInY2T/iDkPQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}